Two-state chronograph with switching means

ABSTRACT

The invention concerns a chronograph watch movement, comprising a chronograph mechanism, including: a chronograph gear-train comprising first ( 40 ) and second ( 38 ) wheels completing a revolution in sixty seconds and a revolution in a fraction of an hour respectively and arranged in the center of the movement, a control device ( 48 ) for starting and stopping the rotation of the chronograph gear-train, and a reset device ( 50 ). In said movement, the chronograph mechanism further comprises switching means designed such that, upon activation, they connect the second wheel ( 38 ) of the chronograph gear-train to a finishing mobile, so that the display means borne by the second wheel display the current time unit equivalent to that of the measured time.

BACKGROUND OF THE INVENTION

The present invention concerns movements for chronograph watches. Suchmovements generally and conventionally comprise a frame, formed of aplate and bridges, and, carried by the frame:

-   -   an energy source,    -   a time base powered by the energy source,    -   a first, going train, driven in rotation in synchronism with the        time base, and comprising a mobile for units of time selected        from among the minutes and hours of the current time, and    -   a chronograph mechanism, which includes:        -   a second, chronograph train, to be driven upon demand, in            synchronism with the time base and comprising first and            second wheels respectively completing one revolution in            sixty seconds and one revolution in a time allowing the            units of measured time, selected from among the hours and            minutes, to be displayed and arranged coaxially with the            first mobile, these wheels being arranged so that they can            carry display means for displaying a measured time, for            example hands, for indicating respectively the measured time            seconds and the selected unit of the measured time,        -   a control device for starting and stopping the rotation of            the second train, and        -   a device for resetting the display means.

Chronographs allow time intervals to be measured, by pressure on one ortwo push-buttons, mounted so as to slide on the watchcase, which controlthe chronograph mechanism. Successive applications of pressure assurethe starting and stopping of the chronograph train, and consequently thestart and end of the measurement.

The measured time is displayed by a chronograph second hand, carried bythe first wheel of the chronograph train. Depending upon the type ofchronograph, the first wheel also drives a wheel completing onerevolution in thirty or sixty minutes and capable of carrying a measuredtime minute hand. This wheel is generally off-centre, such that thechronograph minute hand is smaller than the chronograph second hand.

Thus, in order to facilitate reading of the measured time minute, it isadvantageous to have the chronograph minute hand at the centre of themovement. To prevent it being confused with the chronograph second hand,it has to be wider. As a result it tends to conceal the dial in themidday position when it is not operating. This can be inconvenient forreading the information given by the hands that are situated underneath,namely those for displaying the current time. It is an object of thepresent invention to overcome this drawback.

SUMMARY OF THE INVENTION

This object is achieved owing to the fact that the chronograph mechanismfurther includes switching means arranged so that they can occupy twostates and in one of which they connect the second wheel of thechronograph train to the going train mobile, so that the display meanscarried by the second wheel display the unit of the current timeequivalent to that of the measured time.

Advantageously the unit of time displayed by the mobile and the secondwheel mentioned hereinbefore is the minute. Consequently, while thefirst member connects the chronograph train wheel for displaying theminutes and the current time minute mobile, the minute hand, carried bythe chronograph train wheel, is in a position corresponding to thedisplay of the current time minutes.

More specifically, the switching means comprise a hammer pivotablymounted on the current time minute mobile, a cam secured to the secondchronograph train wheel and an elastic member holding the hammerabutting against the cam.

In order to guarantee that the switching means operate perfectly asdefined hereinbefore, the chronograph mechanism further includes anisolation device, which comprises:

-   -   an isolation mobile provided with a first plate, of the same        diameter as the first mobile, and a second plate arranged for        cooperating with a pawl or click and carrying a pin for        activating the hammer,    -   a retaining member comprising a lever and a retaining wheel,        mounted to be mobile in rotation on the lever and comprising        first and second plates arranged to be able to mesh respectively        with the first plate of the isolation mobile and the going train        minute mobile, and connected to each other by a one-directional        coupling mechanism, and    -   isolation control members comprising:        -   an isolation lever,        -   a pawl pivotably mounted on the lever and cooperating with            the second plate of the isolation mobile, to move it with            reference to the first plate, and with it the pin, which            raises the hammer to interrupt the connection between the            second wheel of the chronograph train and the going train            minute mobile.

At the start of a time measurement, the chronograph second and minutehands must be at zero, to allow the user to know that his counter hasbeen initialised. This could not happen when the measured time minutehand is superposed with the current time minute hand. Thus, in order toprevent any problem of comprehension as to operation, the chronographmechanism further a locking device arranged for locking the control andreset devices while the switching means are connecting the second wheelof the chronograph train to the going train mobile.

In a first variant, the current time minute mobile is arranged to carrya current time minute hand and the second wheel of the chronographtrain, a measured time minute hand. In this variant, when the switchingmeans are in the state in which they connect the second wheel of thechronograph train to the going train mobile, the hands carried by thewheel and mobile are superposed.

In a second variant, only the second wheel of the chronograph traincarries a hand, such that this hand displays the current time minuteswhile the locking device is locking the control device, and the measuredtime minutes in the opposite case. The information provided is thusreduced, but the watch is thinner, which improves its aestheticappearance. It offers the advantage of providing a measured time minutedisplay via a large hand, while only having three hands at the centre ofthe movement, namely those displaying the current time hour, the currenttime minute and the measured time minute as well as the measured timesecond.

Other advantages and features of the invention will appear from thefollowing description, made with reference to the annexed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a watch fitted with a movement according to the invention,in a state in which a measured time measurement is being carried out,

FIG. 2 is a logic operating diagram of the movement according to theinvention,

FIG. 3 is a cross-section of the movement according to the invention,

FIGS. 4 a to 4 d show the dial side of the movement, in various statescorresponding to the steps defined in the diagram of FIG. 2, and

FIG. 5 illustrates the back cover side of the movement, when thechronograph function is locked.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following description, the position of certain components issometimes defined with reference to a time. This position corresponds tothe position on the dial occupied by the hour symbol displaying thegiven time.

The watch shown in FIG. 1 is of the chronograph type. It comprises, in aconventional manner, a case 10 acting as housing for a movement, whichcarries a dial 12, a current time hour hand 14, a current time minutehand 16, measured time minute hand 18 and a measured time second hand20.

The current time display is corrected by means of a time setting crown22, connected to members of the movement by a time setting stem that isnot visible in the drawing.

The timing related functions are performed by three push-buttons 24, 26and 28 respectively disposed at two o'clock, four o'clock and eighto'clock. Push-button 24 controls the starting and stopping of a measuredtime measurement, whereas push-button 26 resets hands 18 and 20 when ameasured time measurement has been interrupted. Finally, push-button 28is for making the chronograph mechanism pass from a first state, inwhich it is locked, into a second state in which it is unlocked.

As will be explained hereinafter, the chronograph mechanism is arrangedso that, when it is locked, current time minute hand 16 and measuredtime minute hand 18 are superposed and rotate together, whereas measuredtime second hand 20 is at midday. In this state, push-buttons 24 and 26are inactive.

FIG. 2 illustrates the effect of the various push-buttons depending uponthe states of the chronograph mechanism, which are identified by acapital letter surrounded by a circle. An application of pressure ontopush-buttons 24, 26 and 28, respectively corresponds to the indicationsP1, P2 and P3 of the Figure.

In the initial state, identified by A and corresponding to the situationillustrated by FIGS. 4 a and 4 b, the chronograph mechanism is locked.The chronograph second hand 20 is at midday and measured time minutehand 18 is superposed on current time minute hand 16, push-buttons 24and 26 being inactive.

An application of pressure P3 causes the chronograph mechanism tounlock. As a result, measured time minute hand 18 leaves current timeminute hand 16 to align at twelve o'clock, thus being superposed on themeasured time second hand 20. This state, shown in FIG. 4 c, isidentified by the letter B.

In this state, push-buttons 24 (P1) and 28 (P3) are active. Anapplication of pressure P1 has the effect of starting the counting of ameasured time, the measured time second hand 20 starting to rotate and,more slowly, measured time minute hand 18. This state, shown in FIG. 4 dand identified by the letter C, brings the display to the situationillustrated in FIG. 1.

In state B, an application of pressure P3 returns the chronographmechanism to its initial state A.

In state C, only push-button 24 is active. An application of pressure P1has the effect of stopping counting of the measured time. Hands 18 and20 thus stop in the position corresponding to the measured time, whichcorresponds to state D, which differs from state B only in that thehands are not at zero.

Another application of pressure P1 then has the effect of restartingcounting, the mechanism thus returning to state C, whereas anapplication of pressure P2 returns hands 18 and 20 to midday, whichcorresponds to state B.

In a variant, achieved by means of a movement like that described withreference to FIGS. 3 to 5, current time minute hand 16 is omitted.Consequently, the current time is read by means of current time hourhand 14 and minute hand 18 while the movement is in state A, whereas inthe other states, minute hand 18 displays the measured time, the currenttime minutes having to be evaluated from the position of current timehour hand 14.

In FIGS. 4 and 5 and in order to avoid overloading the drawings, thesprings have only been shown schematically, by means of an arrow showingthe force that they generate, associated with a reference Fi, “i” beingequal to the reference of the part on which the spring is acting. Theyare essentially visible in FIG. 4 b.

More precisely, FIGS. 4 a and 4 b show the mechanism in its restposition, corresponding to state A, and FIGS. 4 c and 4 d in positionscorresponding respectively to states B and C of FIG. 2. In FIGS. 4 a to4 d, which show the dial side of the movement, some parts have beenremoved or partially torn away from one or other of these Figures, inorder for the subjacent parts to be seen more clearly.

The terms “wheel” or “mobile” are used to differentiate between thecomponents of the chronograph train and going train respectively.

The movement of the invention comprises, in a conventional manner thatis not visible in the drawing, an energy source such as a barrel, a timebase such as a sprung balance, a going train of which only one mobile 29is visible in FIGS. 3 and 4, and an escapement connecting the goingtrain to the balance in order to maintain the latter, as well as timesetting and chronograph mechanisms. These various components of themovement are disposed on a frame 30, formed of a plate and bridges,which assures the relative positioning of the various mobile parts ofthe movement.

FIG. 3 shows the central part of the movement, seen in cross-sectionalong the line III-III of FIG. 4 a, with an axis A-A corresponding tothe axis about which the hands pivot. Frame 30 carries, rigidly securedto its dial side face, a tube 32 comprising a seat 32 a secured to frame30 and two cylindrical portions 32 b and 32 c, whose axis merges withaxis A-A, and arranged one after the other, connected by a shoulder 32 dand designed to act as a fixed arbour for the pivoting of the mobilesand wheels, as will be explained hereinafter.

A current time minute mobile 34 is pivotably mounted so as to pivot ontube 32. It is provided with a pipe 34 a engaged on cylindrical portion32 b of tube 32 and a plate 34 b including a toothing 34 c at itsperiphery. Pipe 34 a, plate 34 b and toothing 34 c are made in a singlepiece.

Mobile 34 meshes permanently, via its toothing 34 c, with mobile 29 ofthe going train, in a gear ratio selected such that it completes onerevolution per hour of current time.

Plate 34 b is provided with:

-   -   a cut out part 34 d in the form of an annular portion covering        an angle of approximately 50°, the function of which will be        specified hereinafter,    -   a stud 34 e, to which a connecting hammer is secured, and    -   a spring tending to return hammer 36 to the centre and        schematically represented by arrow F36 (FIG. 4 b).

A minute hand wheel 38 is pivotably mounted on cylindrical portion 32 cof tube 32. This wheel 38 is only visible, in plan, in FIG. 4 c. Itcomprises a plate 38 a provided, at its periphery, with a toothing 38 b,and a pipe 38 c engaged on tube 32 and extending upwards sufficientlyfor its free end to be released and to allow minute hand 16 to besecured. The latter displays both the current time and the measuredtime, as will be explained hereinafter. Pipe 38 c extends underneathplate 38 a. A cam 38 d, generally called a heart-piece, and moreparticularly visible in plan in FIGS. 4 a, 4 b and 4 d, is secured bybeing driven in or welded thereto. Its lower face abuts against shoulder32 d. This cam 38 d is arranged such that it can cooperate with hammer36, as will be explained hereinafter.

The movement comprises an isolating device whose components' referencestarts with 39 and which includes an isolation mobile 391 mounted onpipe 34 a, a lever 392, a retaining wheel 393 pivotably mounted on lever392, an isolation lever 394 and a pawl or click 395 mounted on lever 394(FIG. 4 a).

Mobile 391 comprises two superposed plates 391 a and 391 b, rigidlyconnected to each other and provided at their periphery with toothingsrespectively referenced 391 c and 391 d, and a pin 391 e secured inplate 391 a. This lower plate is provided with wolf teeth, clearlyvisible in FIG. 4 a, whereas toothing 391 d, of upper plate 391 bcomprises the same number of teeth and has the same profile and samediameter as toothing 34 c. Pin 391 e is engaged in cut out part 34 d andextends as far as hammer 36.

Retaining lever 392 is mounted on frame 30, pivoting in its median part.It carries, at one of its ends, wheel 393 which can rotate on a stud 392a driven into lever 392, whereas the other end forms a nose 393 b which,as will be explained hereinafter is for controlling the movement oflever 392. A spring F392 tends to apply nose 392 b onto a supportsurface.

As shown schematically in FIG. 3, wheel 393 is formed of two plates 393a and 393 b, connected to each other by a click 393 c and respectivelycapable of being meshed with toothings 34 c and 391 d. Click 393 c isarranged such that, when mobile 34 is rotating in the clockwisedirection, the click is locked, such that plate 393 b drives mobile 391in rotation. If, conversely, it is the latter that is being rotated inthe clockwise direction, only plate 393 b is driven, click 393 cperforming its disconnecting function.

Lever 394 comprises (FIG. 4 a):

-   -   a body 394 a pivotably mounted on frame 30, by the engagement of        a hole 394 b made at one of the ends of body 394 a of the lever        in an unreferenced stud, secured to frame 30,    -   a nose 394 c, located in proximity to hole 394 b for controlling        the movement of lever 394,    -   a stud 394 d driven into the body at the opposite end to that        provided with hole 394 b, on which pawl 395 pivots, and    -   a pin 394 e, forming a stop member and limiting the movement of        pawl 395.

Lever 394 is positioned by nose 394 c abutting against a supportsurface, via the action of a spring F394. A spring F395 tends to holdpawl 395 abutting against pin 394 e.

Isolation mobile 391 can be moved by an angle of approximately 45° withrespect to mobile 34, by the engagement of pawl 395 in toothing 391 c.During this movement, pin 391 e, moving freely in cut out part 34 d,raises hammer 36 whose free end is brought back towards the exterior.

When the chronograph mechanism is locked, by means that will beexplained hereinafter, hammer 36, positioned by spring F36, which tendsto apply it against cam 38 d, performs the function of connecting memberbetween mobile 34 and wheel 38, which are thus secured to each other inrotation. This thus means that minute hand 18, carried by pipe 38 c ofwheel 38, displays the minutes of the current time.

In order to count the measured time, the movement shown in the drawingcomprises a chronograph second hand 40, pivotably mounted in tube 32,visible in FIG. 5 and partially in FIG. 3, and a sliding gear 42 (FIGS.3 and 4 c). Wheel 40 comprises an arbour 40 a pivotably mounted in tube32 and in frame 30, a plate 40 b driven onto arbour 40 a and providedwith a toothing, a cam 40 c, also driven onto arbour 40 a, and a drivefinger 41.

The chronograph mechanism further includes a coupling mechanism, notvisible in the drawing, provided with a wheel which, when thechronograph mechanism is in state C, kinematically connects wheel 40 tothe going train, such that it is driven in rotation, at a rate of onerevolution per minute. Such a coupling mechanism is well known to thoseskilled in the art.

Slide gear 42 comprises an arbour 42 a (FIG. 3) rotatably mounted in ajewel 43, with an olive jewel-hole, driven onto a bridge of frame 30 andonto a lever 44, itself pivoting on frame 30 and which will be describedin more detail hereinafter. It further comprises two wheels 42 b and 42c, for cooperating respectively with finger 41 and wheel 38. Dependingupon the position that lever 44 occupies, wheel 42 b is either in thespace swept by finger 41 or not. Moreover, wheel 42 c is permanentlymeshed with toothing 38 b. Lever 44 tends to move in the direction ofthe centre of the movement via the effect of a spring F44 (FIG. 5).

When the chronograph mechanism is in one of states B, C or D, hammer 36is raised by pin 391 e, such that it is no longer abutting against cam38 d. Mobile 34 and wheel 38 are thus no longer secured in rotation.Moreover, when the mechanism is in state C, arbour 42 a is arrangedparallel to axis A-A and its wheel 42 b can be driven in rotation byfinger 41, at a rate of one step for each revolution of wheel 40. Inother words, slide gear 42 performs the function of a connecting memberbetween measured time second wheel 40 and wheel 38, so that the latterdisplays the measured time minutes when the mechanism is in state C orD.

The connecting members formed by hammer 36, spring F36 and cam 38 d onthe one hand, and slide gear 42 on the other hand, perform together thefunction of switching means.

Since current time minute mobile 34 is permanently rotating, driven bythe going train, isolation mobile 391 has to rotate with it, otherwisehammer 36 cannot be controlled. Therefore, retaining wheel 393 is madeto mesh with toothings 34 c of mobile 34 and 391 d of isolation mobile391, the two plates 393 a and 393 b being secured to each other inrotation by click 393 c.

In order to perform the functions as defined with reference to FIG. 2,the chronograph mechanism shown in FIGS. 4 and 5 comprises, in additionto the gear trains and the isolation device described hereinbefore:

-   -   a switch for enabling or disabling the timing function, and        whose constituent parts are defined by references starting with        46,    -   a control device, controlling the starting and stopping of a        measurement, and whose constituent parts are defined by        references starting with 48, and    -   a reset device, for reinitialising the measured time counters,        and whose constituent parts are defined by references starting        with 50.

It should be noted that these devices interact and that some parts arearbitrarily defined as forming part of one device rather than another.

Switch 46 is controlled by push-button 28. It allows minute hand 16 tobe returned to zero, and push-button 24 to be made active. It comprises,for this purpose (FIG. 4 a):

-   -   a switching member 461, comprising:        -   a bird-shaped body 461 a, with a head 461 b provided with a            hole 461 c in which there is engaged a stem passing right            through frame 30 and carrying a finger 461 d visible in FIG.            5, a beak 461 e, two wings 461 f and 461 g, wing 461 g being            provided with a pin 461 h, and a tail 461 j, the head being            disposed on the centre side of the movement and tail 461 j            at the periphery, in proximity to 7 o'clock,        -   a lever 461 k pivotably mounted on tail 461 j and extending            over the periphery of the movement from 7 to 9 o'clock,            provided with a pin 461 m disposed so that it is or is not            located on the path travelled by push-button 28, when it is            activated depending upon the position occupied by lever 461            k, and a stop member 461 n arranged at its free end,        -   a pawl 461 p pivotably mounted on lever 461 k and limited in            its movement by stop member 461 n,    -   a switching cam, for example a column wheel 462, shown        schematically, controlled in rotation by pawl 461 p, rotating on        frame 30 at 462 a, and cooperating with noses 392 b of lever 392        and 394 c of lever 394,    -   an interlocking lever 464, comprising a body of elongated shape        464 a, pivotably mounted on frame 30 in its median part, and one        of whose ends is provided with a nose 464 b arranged for        cooperating with the columns of wheel 462, whereas the other end        comprises a first oblong hole 464 c in which a stud 465 is        mounted to slide, for cooperating with control device 48, and a        second oblong hole 464 d, in which a pin 466 with a head is        housed, itself secured to frame 30, for positioning the lever in        the plane of the movement.

The constituent parts of switch 46 are positioned by springs shownschematically in FIG. 4 b and more particularly:

-   -   body 461 a by spring F461 a,    -   lever 461 k by spring F461 k which tends to return it when        pressure has been applied to push-button 28,    -   pawl 461 p by spring F461 p which holds it pressed against pin        461 n,    -   body 464 a by spring F464 a, which tends to apply nose 464 b        against wheel 462, and    -   stud 465 by spring F465, which tends to press it on the external        side of oblong hole 464 c.

Control device 48 is more particularly visible in FIG. 5. It comprises:

-   -   a control lever 481 comprising:        -   a body 481 a disposed at the periphery of the movement from            2 to 7 o'clock, which pivots at 481 b on frame 30 slightly            below 4 o'clock, and which is provided, at one of its ends,            with a bent portion 481 c extending into the thickness of            stud 465, and        -   a pawl 481 d, pivotably mounted on the other end of body 481            a, whose function will be specified hereinafter,    -   a cam 482, for example of the column wheel type, driven by pawl        481 d, which controls the coupling mechanism of the chronograph,        not shown in the drawing, and positions switching member 461 via        its finger 461 d.

The constituent parts of control device 48 are positioned by springs andmore particularly:

-   -   body 481 a, by spring F481 a which tends to return it when        pressure has been applied to push-button 24, and    -   pawl 481 d, by spring F481 d, which applies it against cam 482.

Reset device 50 comprises:

-   -   a reset lever 501 (FIG. 4 a) arranged and pivotably mounted at        the periphery of frame 30 and extending from 4 o'clock to 6        o'clock, provided at its end in proximity to 4 o'clock with a        pin 501 a for cooperating with push-button 26, and at its other        end with a groove 501 b for cooperating with pin 461 h,    -   a hammer 502 for resetting the minutes arranged in proximity to        column wheel 462 and extending as far as the central part of the        movement to cooperate with cam 38 d via a support surface 502 a        provided with:        -   a nose 502 b which cooperates with column wheel 462, and        -   a pin 502 c for cooperating with wing 461 f, and    -   a hammer 503 for resetting the seconds (FIG. 5) pivotably        mounted on the opposite face of frame 30 in proximity to cam        482, provided with:        -   a nose 503 a cooperating with cam 482,        -   a retaining finger 503 b cooperating with lever 44 via a pin            44 a comprised in the latter, and        -   a support surface 503 c for returning the second hand to            zero by abutting against cam 40 c.

The constituent parts of reset device 50 are positioned by springs andmore particularly:

-   -   lever 501 by spring F501, which tends to return it after        pressure has been applied on push-button 26,    -   hammer 502 by spring F502, which tends to apply support surface        502 a against cam 38 d, and    -   hammer 503 by spring F503, which tends to apply it against cam        40 c.

The movement further comprises a current time hour mobile 52, pivotablymounted on pipe 38 c of minute hand wheel 38. Mobile 52 carries currenttime hour hand 14. It is kinematically connected to mobile 34 by amotion work, which divides the movement by a factor of 12. This motionwork has not been shown to avoid overloading the drawing.

When the chronograph mechanism is at rest, namely in state A definedwith reference to FIG. 2, its constituent parts are in the positionshown in FIGS. 4 a, 4 b and 5. More particularly, nose 392 b ofretaining lever 392 is between two columns of column wheel 462 via theeffect of spring F392, such that retaining wheel 393 is not meshed withtoothings 34 c and 391 d. Nose 394 c of lever 394 is also between twocolumns via the effect of spring F394, so that pawl 395 is withdrawnfrom toothing 391 c. Thus, via the action of spring F36, hammer 36 isabutting against cam 38 d. Wheel 38 of the minute hand is rotating,consequently, in synchronism with current time minute mobile 34.

The interlocking lever 464 is abutting, via its nose 464 b and via theeffect of spring F464 a, against a column of wheel 462, such that stud465 is not inserted between push-button 24 and bent portion 481 c, whichdisables push-button 24. Moreover, an action on push-button 26 causeslever 501 to pivot, but without it acting on any of the other parts.

An application of pressure on push-button 28 activates pin 461 m, whichdrives with it lever 461 k, which causes the chronograph mechanism toswitch. More precisely, the tipping of lever 461 k drives pawl 461 p,which rotates column wheel 462 and generates the following movements,which occur practically simultaneously or in the following order:

-   -   nose 392 b of retaining lever 392 is raised by a column, which        causes wheel 393 to mesh with toothings 34 c and 391 d;    -   nose 394 c of lever 394 is raised, such that pawl 395 meshes        with toothing 391 c, driving in rotation, clockwise, mobile 391        and the single plate 393 b, plate 393 a, meshed with mobile 34,        being disconnected, because of click 393 c;    -   during the relative movement of mobile 391 with reference to        mobile 34, pin 391 e raises hammer 36, such that cam 38 d of        wheel 38 is no longer maintained in phase with mobile 34;    -   nose 502 b of hammer 502 falls, via the effect of spring F502,        between two columns of wheel 462, support surface 502 a        cooperating with cam 38 d such that wheel 38, which carries hand        18, brings the latter to midday, and    -   nose 464 b of interlocking lever 464 falls between two columns        of wheel 462 via the effect of spring F464 a, bringing stud 465        between push-button 24 and bent portion 481 c.

The mechanism is then in state B defined in FIG. 2 and shown in FIG. 4c. The connecting member formed by hammer 36 and cam 38 d then no longerprovides a connection between wheel 38 and mobile 34. Switch 46 thusplays the part of control member, and deactivates the connecting member.

In this state, push-buttons 24 and 28 are operational. If push-button 28is pressed again, lever 461 k, tips and drives pawl 461 p. This causescolumn wheel 462 to rotate, which generates the following movements,which occur practically simultaneously or in the following order:

-   -   nose 392 b of retaining lever 392 falls between two columns of        wheel 462 via the effect of spring F392, wheel 393 thus being        released from toothings 34 c and 391 d;    -   nose 502 b is raised by a column, such that hammer 502 releases        cam 38 d;    -   nose 394 c falls back between two columns and lever 394 returns        to the position shown in FIG. 4 a via the effect of spring F394;    -   via the effect of spring F36, hammer 36 tips and abuts against        pin 391 e, which causes isolation mobile 391 to rotate, then        against cam 38 d which drives wheel 38 until hand 18 again        displays the minutes of the current time; and    -   nose 464 b of interlocking lever 464 is raised by a column of        wheel 462 such that stud 465 leaves the space comprised between        bent portion 481 c and push-button 24.

The mechanism has thus returned to state A shown in FIG. 4 a.

From state B, shown in FIG. 4 c, it is also possible to actuatepush-button 24, which has the effect of starting a measured timemeasurement. More specifically, push-button 24 abuts against stud 465,which slides into oblong hole 464 c and, applied against bent portion481 c, causes body 481 a of lever 481 to pivot. Its pawl 481 d, moreparticularly visible in FIG. 5, causes cam 482 to rotate through onestep. This movement of cam 482 generates the movements describedhereinafter, which occur practically simultaneously or in the followingorder:

-   -   hammer 503, visible in FIG. 5, is raised via its nose 503 a,        such that support surface 503 c is released from cam 40 c;    -   the chronograph coupling mechanism causes the coupling wheel to        mesh both with the going train and the chronograph second wheel        40, so that the latter is driven in rotation and, with it,        chronograph second hand 20;    -   retaining finger 503 b releases pin 44 a from lever 44, such        that spring F44 causes lever 44 to pivot, wheel 42 b being then        positioned such that it is in the space swept by finger 41,        which can then rotate slide gear 42 and, via the latter, minute        hand wheel 38, at a rate of one step per minute, and    -   finger 461 d is raised by a column of cam 482, which causes body        461 a (FIG. 4 b) and lever 461 k of switching member 461 to tip.        Consequently, pin 461 m is shifted with respect to push-button        28, thus disabling the latter. Moreover, wing 461 f raises        hammer 502 via its pin 502 c, thus allowing minute hand wheel 38        to rotate.

Moreover, the pivoting of body 461 a brings its pin 461 h into groove501 b of reset lever 501. During this operation, the connecting memberformed by slide gear 42, controlled by control device 48 via hammer 503,passes from the deactivated state to the activated state.

The mechanism is then in the position shown in FIG. 4 d, whichcorresponds to state C of FIG. 2. In this state, only push-button 24 isactive. In fact, pin 461 m is shifted with respect to push-button 28,which disables the latter. Moreover, body 461 a, whose position isdefined by finger 461 d abutting against a column of cam 482, remains inthis position, even if groove 501 b releases pin 461 h. In other words,an application of pressure on push-button 26 has no effect.

An application of pressure on push-button 24 causes it to abut againststud 465 which slides into oblong hole 464 c and, applied against bentportion 481 c, causes lever 481 to pivot. Its pawl 481 d (FIG. 5) causescam 482 to rotate through another step. This movement of cam 482generates the movements described hereinafter, which occur practicallysimultaneously, or in the following order:

-   -   the chronograph coupling mechanism is moved, such that        chronograph second wheel 40 is no longer connected to the going        train, which means that it stops;    -   finger 461 d passes from abutting against a column of cam 482 to        a position in which it is between two columns, without, however,        body 461 a and finger 461 d pivoting, since body 461 a is        retained by pin 461 h engaged in groove 501 b of lever 501; and    -   nose 502 a of hammer 502 is between two columns of wheel 462,        but it does not change position, because of pin 502 c which is        abutting against wing 461 f of body 461 a.

Hammer 503 is retained by similar means to those retaining hammer 502,but they have not been shown in order to avoid overloading the drawing.The chronograph mechanism is then in state D of the logic diagram ofFIG. 2. This state, which is not shown in the drawing, allows action onpush-buttons 24 and 26. An application of pressure on push-button 24starts the time count, the mechanism returning to state C via anotherrotation of cam 482. Thus, the chronograph coupling mechanism is coupledagain, whereas nose 503 a of the hammer and finger 461 d are abuttingagainst a column of cam 482.

When the mechanism is in state D, an application of pressure onpush-button 26 drives lever 501 which, by pivoting, releases pin 461 h.Since finger 461 d is between two columns of cam 482, nothing is holdingit any longer, such that spring F461 a returns switching member 461 tothe position shown in FIG. 4 b. Moreover, hammer 502 is no longer heldby wing 461 f, such that its spring F502 causes it to tip and abutagainst cam 38 d, which has the effect of resetting minute hand 18 tozero.

A similar process is applied to hammer 503, such that cam 40 c is alsosubjected to a force that returns measured time second hand 20 tomidday. The chronograph mechanism is then again in state B definedhereinbefore, such that it is possible to press on push-button 28, toreturn the mechanism to state A, where push-buttons 24 and 26 aredisabled and where minute hand 18 displays the minutes of the currenttime. It is also possible to press on push-button 24 in order to start anew measurement, the mechanism then being in state C.

The mechanism described with reference to FIGS. 3 to 5 comprises onlyone minute hand, which either displays the current time, or the measuredtime. It would also be possible, with a minor alteration, to have a hand16 permanently displaying the current time minutes, whereas hand 18displays the measured time minutes, as shown in FIG. 1. In order to dothis, one need only provide mobile 34 with a pipe extending in thedirection of the dial and which would insert the end thereof carryinghand 16 between pipe 38 c of wheel 38 and tube 32.

Many other variants can also be envisaged, wherein the constituent partsof the members of the chronograph mechanism could take other forms andcooperate very differently, without thereby departing from the scope ofthe invention. Thus, column wheels 462 and 482 could advantageously bereplaced by pivoting cams. It would also be possible to use an axialand/or friction coupling device, instead of mobile 42.

It is also entirely possible to envisage placing the current time hourhand off-centre and keeping only the measured time minute and secondhands and the current time minute hand at the centre of the movement.

It is evident that the principle described is also applicable to thecurrent time and measured time hour display, the hour hands either beingcentral or off-centre.

In a variant that has not been described, it is also possible to omitswitch 46, and consequently push-button 28, such that, when push-button26 is activated, second hand 20 starts to rotate whereas minute hand 18passes from the position where it is superposed on hand 16 to alignmentat midday.

Thus, owing to the features described in the chronograph mechanismforming the subject of the present invention, it is possible to make awatch wherein the measured time minute and/or hour hand does notoverload the display during the time when the mechanism is not inoperation. Moreover, the mechanism enables the start, stop and resetfunctions to be locked, when there is no measurement being carried out.

1. A chronograph watch movement, including a frame and, carried by theframe, the chronograph watch movement comprising: an energy source, atime base powered by the energy source, a first going train elementdriven in rotation in synchronism with said time base, said first goingtrain element including a mobile element associated with units of timeselected from among the minutes and hours of the current time; and achronograph mechanism including: a second chronograph train element fordriving in synchronism with the time base, said second chronograph trainelement including first and second wheels respectively completing onerevolution in sixty seconds and one revolution in a time allowing themeasured units of time, selected from between the hours and minutes, tobe displayed, said first wheel and said second wheel being arrangedcoaxially with said mobile element, said wheels being arranged such thatsaid wheels carry display means for displaying a measured time; acontrol device for starting and stopping said wheels of said secondtrain; a device for resetting the display means; and a switching meansfor switching between a connected state and a disconnected state suchthat said second wheel of said chronograph train is connected to saidmobile element of said going train element when said switching means isin a connected state, whereby said display means connected to saidsecond wheel displays the unit of current time equivalent to themeasured time, said unit of current time and said unit of measured timebeing a minute, said switching means including a hammer pivotablymounted on the mobile element, a cam secured to the second wheel and anelastic member holding the hammer abutting against the cam.
 2. Amovement according to claim 1, further comprising an isolation deviceincluding: an isolation mobile element including a first plate of thesame diameter as the first mobile, and a second plate arranged forcooperating with a pawl and provided with a pin for activating thehammer; a retaining member comprising a lever and a retaining wheel,mounted to be mobile in rotation on the lever and comprising first andsecond plates arranged to be able to mesh respectively with the firstplate of the isolation mobile and the minute mobile of the first trainelement, and connected to each other by a one-directional couplingmechanism, and isolation control members comprising: an isolation lever,a pawl pivotably mounted on the lever and cooperating with the secondplate of the isolation mobile element, to move it with reference to thefirst plate, and with it said pin, which raises the hammer to interruptthe connection between the second wheel of the second train and theminute mobile of the going train.
 3. A movement according to claim 1,wherein the chronograph mechanism further includes a locking devicearranged for locking the control device while the switching means areconnecting the second wheel of the second train element to said mobileelement.
 4. A movement according to claim 3, wherein said mobile elementis connected to a current time minute hand and the second wheel ameasured time minute hand, such that, while the locking device islocking the control device, the switching means position the secondwheel with reference to the first mobile such that the two hands aresuperposed.
 5. A movement according to claim 3, wherein only the secondwheel carries a minute hand, such that said minute hand displays thecurrent time minutes while the locking device is locking the controldevice, and the measured time minutes in the opposite case.
 6. Achronograph watch movement, including a frame, the chronograph watchmovement comprising: an energy source; a time base powered by the energysource; a current time measuring hand a first drive train rotating insynchronization with said time base, said first drive train elementincluding a first gear connected to said current measuring time hand; achronograph mechanism including: a first display means; a second displaymeans; a second chronograph drive train actuated in synchronism withsaid time base, said second chronograph drive train including a firstchronograph gear and a second chronograph gear, said first chronographgear completing one revolution in sixty seconds, said second chronographgear completing one revolution in sixty minutes, said first chronographgear and said second chronograph gear being arranged coaxially with saidfirst gear of said first drive train, said first chronograph gear beingconnected to said first display means, said second chronograph gearbeing connected to said second display means; a control means forcontrolling said first chronograph gear and said second chronographgear; a resetting means for resetting said first display means and saidsecond display means; and a switching means for switching between aconnected state and a disconnected state such that said secondchronograph gear of said chronograph drive train is connected to saidfirst gear of said first drive train when said switching means is insaid connected state, said second display means being superimposed withsaid current measuring time hand when said second chronograph gear isconnected to said first gear, said unit of current time and said unit ofmeasured time being a minute, said switching means including a hammerpivotably mounted on the first gear, a cam secured to the second wheeland an elastic member holding the hammer abutting against the cam.
 7. Amovement according to claim 6, further comprising an isolation deviceincluding: an isolation gear including a first plate of the samediameter as the first gear, and a second plate arranged for cooperatingwith a pawl and provided with a pin for activating the hammer; aretaining member comprising a lever and a retaining wheel mounted forrotation on the lever, said retaining member including first and secondplates arranged such that said first and second plates mesh respectivelywith the first plate of the isolation gear and the minute gear of thefirst train drive, and connected to each other by a one-directionalcoupling mechanism, and isolation control members comprising: anisolation lever, a pawl pivotably mounted on the lever and cooperatingwith the second plate of the isolation gear to move said pawl withrespect to the first plate and said pin, said pin raising the hammer tointerrupt the connection between the second wheel of the second drivetrain and the minute gear of the first drive train.
 8. A movementaccording to claim 6, wherein the chronograph mechanism furthercomprises a locking device for locking the control device when theswitching means connects the second chronograph gear of the second drivetrain to said first gear.
 9. A movement according to claim 8, whereinsaid second display means is a measured time minute hand, said lockingdevice locking said control means, said switching means positioning thesecond chronograph gear with respect to said first gear such that thetwo hands are superimposed when said locking device locks said controlmeans.
 10. A movement according to claim 8, wherein only the secondchronograph gear is connected to a minute hand, said minute handdisplaying the current time minutes while the locking device locks saidcontrol device, said minute hand displaying the measured time minuteswhen said locking device unlocks said control device.
 11. A chronographwatch movement, including a frame, the chronograph watch movementcomprising: an energy source; a time base powered by the energy source;a current time measuring hand; a first drive train rotating insynchronization with said time base, said first drive train elementincluding a first gear connected to said current measuring time hand; achronograph mechanism including: a measuring time hand; a second hand; asecond chronograph drive train for driving in synchronism with said timebase, said second chronograph drive train including a first chronographgear connected to said second hand and a second chronograph gearconnected to said measuring time hand, said first chronograph gearcompleting one revolution in sixty seconds, said second chronograph gearcompleting one revolution in sixty minutes, said first chronograph gearand said second chronograph gear being arranged coaxially with saidfirst gear of said first drive train; a control means for controllingsaid first chronograph gear and said second chronograph gear; aresetting means for resetting said measuring time minute hand and saidsecond hand; a switching means for connecting said second chronographgear of said chronograph drive train to said first gear of said firstdrive train, said measuring time hand being superimposed with saidcurrent measuring time hand and rotating therewith when said secondchronograph gear is connected to said first gear, said current time andsaid measured time being measured in minutes, said switching meansincluding a hammer pivotably mounted on the first gear, a cam secured tothe second wheel and an elastic member holding the hammer abuttingagainst the cam.
 12. A movement according to claim 11, furthercomprising an isolation device including: an isolation gear including afirst plate of the same diameter as the first gear, and a second platearranged for cooperating with a pawl and provided with a pin foractivating the hammer; a retaining member comprising a lever and aretaining wheel mounted for rotation on the lever, said retaining memberincluding first and second plates arranged such that said first andsecond plates mesh respectively with the first plate of the isolationgear and the minute gear of the first train drive, and connected to eachother by a one-directional coupling mechanism, and isolation controlmembers comprising: an isolation lever, a pawl pivotably mounted on thelever and cooperating with the second plate of the isolation gear tomove said pawl with respect to the first plate and said pin, said pinraising the hammer to interrupt the connection between the second wheelof the second drive train and the minute gear of the first drive train.13. A movement according to claim 11, wherein said current time minutehand being superimposed with said measuring time hand when saidchronograph mechanism is in said locked state.
 14. A movement accordingto 11, wherein said chronograph mechanism further comprises a lockingmeans for locking and unlocking said control means such that saidchronograph mechanism is in a locked state or an unlocked state, saidchronograph mechanism being in said locked state when said switchingmeans connects said second chronograph gear of said second drive trainto said first gear, wherein a position of said measuring time handdefines a measured time when said control means is in said unlockedstate, said measuring time hand displaying a current time when saidcontrol means is in a locked state, said measuring time hand displayingsaid measured time when said control means is in said unlocked state.15. A chronograph watch movement, including a frame, the chronographwatch movement comprising: an energy source, a time base powered by theenergy source, a first going train element driven in rotation insynchronism with said time base, said first going train elementincluding a mobile element associated with units of time selected fromamong the minutes and hours of the current time; and a chronographmechanism including: a second chronograph train element for driving insynchronism with the time base, said second chronograph train elementincluding first and second wheels respectively completing one revolutionin sixty seconds and one revolution in a time allowing the measuredunits of time, selected from between the hours and minutes, to bedisplayed, said first wheel and said second wheel being arrangedcoaxially with said mobile element, said wheels being arranged such thatsaid wheels carry display means for displaying a measured time; acontrol device for starting and stopping said wheels of said secondtrain; a device for resetting the display means; and a switching meansfor switching between a connected state and a disconnected state suchthat said second wheel of said chronograph train is connected to saidmobile element of said going train element when said switching means isin a connected state, whereby said display means connected to saidsecond wheel displays the unit of current time equivalent to themeasured time, said unit of current time and said unit of measured timebeing a minute; and a locking device arranged for locking the controldevice while the switching means are connecting the second wheel of thesecond train element to said mobile element, said mobile element beingconnected to a current time minute hand and the second wheel beingconnected to a measured time minute hand, such that, while the lockingdevice is locking the control device, the switching means positions thesecond wheel with reference to the first mobile such that the two handsare superposed.
 16. A chronograph watch movement, including a frame, thechronograph watch movement comprising: an energy source; a time basepowered by the energy source; a current time measuring hand; a firstdrive train rotating in synchronization with said time base, said firstdrive train element including a first gear connected to said currentmeasuring time hand; a chronograph mechanism including: a first displaymeans; a second display means; a second chronograph drive train actuatedin synchronism with said time base, said second chronograph drive trainincluding a first chronograph gear and a second chronograph gear, saidfirst chronograph gear completing one revolution in sixty seconds, saidsecond chronograph gear completing one revolution in sixty minutes, saidfirst chronograph gear and said second chronograph gear being arrangedcoaxially with said first gear of said first drive train, said firstchronograph gear being connected to said first display means, saidsecond chronograph gear being connected to said second display means; acontrol means for controlling said first chronograph gear and saidsecond chronograph gear; a resetting means for resetting said firstdisplay means and said second display means; and a switching means forswitching between a connected state and a disconnected state such thatsaid second chronograph gear of said chronograph drive train isconnected to said first gear of said first drive train when saidswitching means is in said connected state, said second display meansbeing superimposed with said current measuring time hand when saidsecond chronograph gear is connected to said first gear; an isolationdevice comprising: an isolation gear including a first plate of the samediameter as the first gear, and a second plate arranged for cooperatingwith a pawl and provided with a pin for activating the hammer; aretaining member comprising a lever and a retaining wheel mounted forrotation on the lever, said retaining member including first and secondplates arranged such that said first and second plates mesh respectivelywith the first plate of the isolation gear and the minute gear of thefirst train drive, and connected to each other by a one-directionalcoupling mechanism, and isolation control members comprising: anisolation lever, a pawl pivotably mounted on the lever and cooperatingwith the second plate of the isolation gear to move said pawl withrespect to the first plate and said pin, said pin raising the hammer tointerrupt the connection between the second wheel of the second drivetrain and the minute gear of the first drive train.